TLDR; nope! Planning and building control don't appear to talk to each other much! "Permitted Development" is a term that planning concern themselves with and essentially means no planning permission is needed provided I stick to under 2.5m in height as I'm less the 1m from the boundary, and don't exceed 50% of the available land around the house. Beyond that for the build I'm doing Planning don't really care. Building control varies council to council but in Poole under 15m2 you're exempt from building regs. Under 30m2 you can still be exempt provided "the building is constructed substantially of non-combustible material". I spoke to building control at BCP and they confirmed it would be exempt provided the walls facing the boundary are "clad internally and externally with a non-combustible material to qualify as being substantially non-combustible". I'm cladding those walls externally with a box profile steel sheet, and internally with fireproof plasterboard which they were happy with.
Here is a link to a guide on permitted development rights if anyone is interested. You can build some fairly large buildings within these regulations. I have built a 9m x 6.5m garage workshop tall enough for a two post ramp inside within the rules of permitted development. https://assets.publishing.service.g...e/830643/190910_Tech_Guide_for_publishing.pdf